1. Comparative Anatomy Nervous System
Kardong
Chapter 16
Part 15

2. Primary Brain Vesicles
Prosencephalon (Forebrain)
Smell
Mesoncephalon (Midbrain)
Vision
Rhombencephalon (Hindbrain)
Hearing
Figure Primary brain vesicles (book figure 16.25).

3. Primary Brain Vesicles (cont.)
Figure Basic brain plan.
Figure Brain divisions.

4. Hindbrain Myelencephalon Medulla oblongata Involuntary reflexes
Vagal lobe
Metencephalon
Cerebellum
Roof of metencephalon
Reflex control of
skeletal muscle
Pons - Floor of metencephalon - relay station of sensory and motor tracts between spinal cord and cerebrum
Figure Regional divisions of the brain
(book figure 16.25).

5. Hindbrain (cont.) 4th ventricle Cavity of hindbrain
Posterior choroid plexus
Roof in hindbrain
4th ventricle tissue
Cerebrospinal fluid
Tela choroidea
Roof of medulla
Thin membrane
Figure Choroid plexus shown in a larval anuran.

6. Brain Divisions/Vesicles
Figure Regions of the vertebrate brain (Fig )

7. Midbrain No subdivisions Roof – tectum; floor - tegmentum Optic lobes
Optic reflex centers
Well developed in birds
Auditory lobes
Caudal to optic lobes
Superior (optic) and inferior (auditory) colliculi- when lobes occur together
Corpora quadrigemina collectively
Figure Mesencephalon and tectum region.

8. Midbrain (cont.) 3rd ventricle Cavity of midbrain Cerebral aqueduct
Restricted passageways
Conduit between
3rd and 4th ventricle
Aqueduct of Sylvius when restricted further
Figure Cerebral aqueduct and ventricles of brain.

9. Forebrain - Diencephalon
Optic chiasma
Two optic nerves cross
Pituitary gland
Caudal to optic chiasma
Saccus vasculosus
Posterior to pituitary in some fish
Depth receptor
Figure Regions of the diencephalon of a shark with third ventricle in red.

10. Forebrain- Diencephalon (cont.)
Hypothalamus
Floor of diencephalon
Thalamus
Walls of diencephalon
3rd ventricle cavity
Communicates with lateral ventricles
Foramen of Monro
(actually 2 foramina)
Figure Medial view of the brain showing thalamus and hypothalamus of the diencephalon.

11. Forebrain- Diencephalon (cont.)
Epithalamus
Several evaginations
Roof of diencephalon
Paraphysis anteriorly
Epiphyseal complex
Pineal
Photoreceptors
Parapineal
Pineal eye (3rd eye)
Figure Epithalamus; gross mid-sagittal section of the human brain.
Figure Pineal in detail
(see book figure 16.37).

12. Forebrain- Telencephalon
Cerebral hemispheres posterior
Rhinencephalon anterior
Olfaction
Lower vertebrates
Rhinencephalon prominent
Hemisphere smaller
Higher vertebrates
Hemispheres increase in size
Olfactory get smaller
Figure Frontal section of cerebral hemisphere formation.

13. Evolution of Vertebrate Brain
Figure Phylogenetic enlargement of vertebrate brains (see Fig ).

14. Vertebrate Brains (cont.)
Figure Dorsal view of vertebrate brains.

15. Telencephalon Terminology

16. Fish Cerebrum Primitive sensory Pallium- dorsal area Motor area
Subpallium- ventral area
Globus pallidus (striatum)
Figure Embryonic development of the telencephalon (Book figure

17. Amphibian Cerebrum Similar pallium and globus pallidus
Split left and right hemispheres
Figure Globus pallidus of amphibian; left cerebral hemisphere.

18. Reptile Cerebrum Cerebrum is huge compared to amphibians
Increase of lateral walls
Pushes into lateral ventricle
Dorsal ventricular ridge forms
Receives visual, auditory, and sensory stimuli
Figure Globus pallidus of reptile and bird; left cerebral hemisphere.

19. Bird Cerebrum Similar to reptiles Avian ridge (hyperstriatum)
Stratum of neurons that capped ridge
Processes visual information
Important to instinctive stereotypic
behavior
Migration and courtship
Figure Globus pallidus of reptile and bird; left cerebral hemisphere.

20. Mammalian Cerebrum Lateral ventricles extremely expanded Neocortex
Higher mental facilities
Grooves (sulci)
Folds (gyrae)
Figure Neocortex of mammalian brain.

21. Mammalian Cerebrum (cont.)
Figure Ventral view of human brain (see book Fig 16.36).

22. Mammalian Cerebrum (cont.)
Portion of primitive brain retained
Ventral medially
Hippocampus- ancient olfactory pallium
Memory storage?
Globus pallidum pushed interiorly
Basal ganglia
Changes in basal ganglia  motor dysfunction
Parkinson’s Disease
Figure Globus pallidus of human; left cerebral hemisphere

23. Mammalian Cerebrum (cont.)
Figure Sagittal section of the human brain (book Fig ).

24. Cranial Nerves Amniotes have 12 Anamniotes have 10
Terminal nerve (Nerve 0)- uncommon in humans
Associated with pheromone receptors
Figure Cranial nerve locations on the brain.

25. Figure 15.25. Cranial nerve innervation
(book Fig ).

26. Figure 15.26. Cranial nerve innervation
(book Fig ).

27. Cranial Nerves (cont.)
Figure Cranial nerves in 6th week embryo.
Figure Head organization in 4th week embryo (book figure 16.39).

28. Cranial Nerves (cont.)

29. Cranial Nerves (cont.)